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Difficulty thinking clearly is one sign of the cognitive impairment some bypass surgery patients experience after surgery. This is called post-perfusion syndrome, referring to the heart-lung machine used to support blood flow during surgery.

“The term that we used to use is ‘pump head, which is the effect on cerebral functioning of having been exposed to the bypass machine,” says cardiologist Dan Fintel, MD, a professor of medicine in the division of cardiology at the Northwestern University Feinberg School of Medicine in Chicago. “There is some evidence of decline in cognitive function, which is generally reversible. For most people it improves within a few months.”

After a bypass surgery, patients may experience:

Stroke (5 to 6 percent of patients). “True strokes are the most feared complication of bypass surgery and particularly in the elderly, are the leading cause of morbidity after bypass,” notes Dr. Fintel.

Vision problems.. “I tell people not to go out and get new glasses or contacts for a few months because their vision will improve,” Fintel says.

Short-term memory loss

Slower thought processes

Difficulty making decisions or solving problems

The older the patient, the greater the risk of cognitive impairment, says Fintel. This may be partly because the process of cognitive impairment has already begun before bypass surgery in patients with heart disease.

Reasons for Cognitive Impairment After Bypass Surgery

Although the phenomenon is not fully understood, there are some theories about why cognitive impairment occurs after bypass surgery:

Development of small clots. “Small clumps of platelets get stuck in the brain and affect vision and thought processes,” explains Fintel. These tiny clots form during the time that the body’s blood flow is supported by a machine during surgery. However, says Fintel, “The brain tends to recover.”

Trauma during surgery. Cross clamping, which is done to close the aorta during surgery, can make plaque break off into the blood stream and cause small strokes.

Genetic risk. Various genetic factors have been linked to an increased risk of cognitive impairment after bypass surgery, but researchers have yet to identify one that could predict cognitive impairment.

Coronary artery disease (CAD). There is some data to suggest that CAD, the heart disease that creates the need for bypass surgery, also causes cognitive decline similar to that resulting from bypass surgery.

Although all of the causes of cognitive impairment after bypass surgery are not yet fully understood, there are some steps that can be taken during surgery to protect the brain, including:

Ultrasound of the aorta. This diagnostic test could help reduce stroke risk.

Using different cross-clamp techniques. A recent study of 169 patients showed that using a single cross-clamp approach reduced the risk of cognitive decline.

While cognitive impairment after bypass surgery usually gets better on its own, it is best not to assume that your experience is normal and that you shouldn’t worry about it. Here’s what to do:

Talk to your doctor. If you’re having problems with speech, vision, memory, or thinking clearly, let your doctor know. You can decide together whether you need to take more aggressive steps to control the situation.

Take the tests. Your doctor may want to give you some tests to find out what kind of cognitive impairment you’re experiencing. You may be asked to count in an odd series of numbers, name days and months, or recall a series of unrelated words. You may also undergo brain imaging. All of these tests help your doctor understand how your brain is working.

Consider medication. Depending on the type of cognitive impairment you’re experiencing and the probable cause, your doctor may recommend blood-thinning medications or drugs used to slow the progression of Alzheimer’s disease.

Go to cardiac rehabilitation. Taking time to participate in a cardiac rehabilitation program means that you will be able to get tips from experts about how to manage various aspects of life after bypass surgery, including diet, physical activity, and cognitive impairment.

Cognitive impairment after bypass surgery is a significant worry for patients — but in most cases it appears to be manageable. Keep the lines of communication open with your doctors before and after surgery so you can stay on top of any risk of cognitive decline.

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